Electron tube tapping apparatus



April 4, 1961 w. s. OAKES ELECTRON TUBE TAPPING APPARATUS Filed Dec. 24, 1958 F IG.I. 22

INVENTOR WILLIAM s OAKES, BY Fa -Ag} V HIS TORNEY.

* United States ELECTRON TUBE TAPPING APPARATUS Filed Dec. 24, 1958, Ser. No. 782,733

7 Claims. (Cl. 324-20) This invention relates to electron tube testing apparatus and more particularly to an improved tapping apparatus for subjecting electron tubes to mechanical shock and vibration.

In the process of manufacturing electron tubes it is important to reject those tubes which will be susceptible to failure during use due to inability to withstand various foreseeable environmental conditions. In this connection it is customary to subject completed tubes to a mechanical shock and vibration test. Often this is accomplished by tapping the envelope of the tube while the tube is connected in a suitable electrical circuit, to thereby reveal the presence of short circuited elements, open circuits, microphonics, radio frequency noise, or other mal-functions of the tube responsive to the mechanical shocks and vibrations produced by the tapping. One of the problems with prior art tube tappers is that not infrequently they fail to reveal those tube malfunctions caused by electrode vibrations which are particularly directionally sensitive, with the result that such susceptibility to mal-function in service goes undetected. It is one of the objects of the present invention to avoid this shortcoming in prior art tube tapping apparatus.

A further object of the present invention is to provide an improved tube tapping apparatus particularly suitable for subjecting electron tubes to shock and vibration testing of the foregoing character under high speed mass production conditions.

Another object is to provide a tube tapping apparatus which is particularly suitable for use in conjunction with high speed quantity production tube handling apparatus including automatically indexed tube conveying devices.

Another object is to provide a tube tapper having an improved ability to detect tube mal-functions resulting from electrode vibrations which are directionally sensitive.

' Another object is to provide an improved electron tube tapping apparatus which is entirely self contained and requires no special external control equipment.

These and other objects of the present invention will be apparent from the following description taken in conjunction with the accompanying drawing wherein:

Figure l is a side elevation view of one form of tube tapping apparatus constructed according to the present invention.

Figure 2 is a perspective view of the structure shown in Figure l.

Briefly, a tube tapping apparatus constructed according to the present invention includes one or more tapping hammers arranged to rotate about the tube envelope duratent.

ing the tapping cycle so as to tap the tube about the entire periphery of its envelope.

Fatented 'Ap 1-951 Referring to Figure 1, the tube tapping apparatus there shown includes a base 2 on which is mounted a drive motor 4 connected by a drive gear 6 and driven gear 8 to a hollow shaft 10 extending through and journaled in a bearing block 12. Gear 8 carries a pin 18 engageable with stops 14, 16 so as to limit rotation of shaft 10 to in either direction from an initial position. Motor 4 is reversible, and may be of any suitable type capable of withstanding stalling or having a slip clutch such as to accommodate stoppage of shaft 19 at its limits of rotation. v

The test apparatus is adapted to'be disposed so that one end of the shaft 10 is situated opposite a tube test position to which tubes are adapted to be indexed in succession by an indexing head 19, with the axis of shaft 10 substantially coaxial with a tube in the test position. 0n the one end of the shaft is secured, as by split collar 20, a plate forming diametrically, oppositely extending arms 22. On the outer end of each arm is an integral flange 24 to which is secured a solenoid 26 having a rotatable armature. On each solenoid armature is mounted a hammer 28 consisting of an L-shaped arm 39 having an enlarged head 32 which may be covered with rubber or other resilient material. The arms 22 and 28 are so dimensioned and arranged that the hammers 25 are adapted to be disposed opposite diametrically spaced points on the envelope of a tube in test position.

Mounted on the other end of the hollow shaft 10 for rotation therewith is a cam 40 arranged to cooperate with and actuate a plurality of stationary electric switches 42, 44 which control the operation of the rotary solenoids 26, so that as the shaft rotates each hammer 28 in sequence is periodically impelled into impact against the envelope of a tube indexed into test position between the hammers. The hammers 28 are spring biased away from impacting position by springs, not shown, within each rotary solenoid 26.

Extending through the hollow shaft 10 is an axially reciprocable rod or plunger 50 connected to the piston of an air cylinder 52 mounted on the base. Movement of the piston of air cylinder is controlled by a solenoid valve 54 on air supply line 56. On the free end of the plunger is secured a pad or shoe 58 of resilient material such as rubber, which may be of tubular configuration as shown.

The operation of the tapper will now be described. The tube tapping apparatus is arranged adjacent the path of the automatically indexing tube conveyor 19, on which tubes are preferably supported and connected in electrical test circuits by base pin receiving sockets, such that tubes may be indexed one at a time into tapping test position. To preclude interference of the hammers with indexing movement of tubes into test position, the initial rotative position'of the shaft is such that the hammers are spaced in a plane substantially normal to the direction of indexing movement of the tubes. After a tube is indexed into the proper position to be tapped, the plunger 50 is extended by the air cylinder 52 so that the shoe 58 engages the free end of the tube envelope, thereby firmly supporting the tube between the shoe and the tube carrying structure of the conveyor so that the tube may be tapped as hard as desired without dislodging it from its test socket. Any envelope tubulation of the tube maybe readily accommodated in the central bore of the tubularly shaped shoe 58, as shown.

that the two hammers 28 in sequence strike and rebound from diametrically opposed points on the tube envelope. Since each hammer 28 operates on half the periphery of the tube envelope, the tube is tapped throughout the entire 360 of its envelope periphery. After the shaft has rotated 180, pin 18 strikes a stop 14, preventing further shaft rotation in the clockwise'direction. This completes the tap test for the first tube, and shaft 10 remains stationary until the next tube is indexed into test position.

The drive motor 4 is then reversed by a suitable switch, not shown, which may preferably be synchronized with indexing of the next tube into tapping test position. The hollow shaft then rotates 180 again, this time in the opposite or counterclockwise direction, and the hammers 2 8 strike diametrically spaced points throughout the periphery of the next tube envelope. When the 180 counterclockwise rotation is complete, the shaft has. returned to its initial position, pin 18 engages limit stop 16, and motor 4 is stalled until the next tube in succession is indexed into tapping test position, whereupon motor 4 will be energized to drive the shaft clockwise again. The limited rotation of shaft 10 avoids the need for slip rings and permits simple flexible cable electrical connections between switches 42, 44 and solenoids 2 6. In practice it has been found that good performance of the test apparatus is obtained with a rate of rotation of the shaft 10 of about A revolution per second, with about 8 taps per hammer 28 during each 180 rotation of the shaft 10.

Tube tapping apparatus constructed according to the present invention has several advantages. As will be apparent, the tube tapping apparatus is entirely self contained, the rotary cam 40 in cooperation with the stationary switches controlling electrically operation of all the movable tapping elements, and no external control is required. Further it may be seen that by rotation of the hammers around the tube envelope during the tapping cycle each tube is tapped throughout the entire periphery of its envelope, and hence mal-functions of a particularly directionally sensitive character will be readily revealed, thereby providing increased assurance of the reliability of the tubes which pass the tap test. Also the split collar 20 permits ready adjustment of the points of impact of the hammers 28 along the axis of a tube under test.

It will be appreciated by those skilled in the art that the invention may be carried out in various ways and may take various forms and embodiments other than those illustrative embodiments heretofore described. It is to be understood that the scope of: the invention is not limited by the details of the foregoing description, but will be defined in the following claims.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. Electron tube testing apparatus comprising a rotor adapted to be disposed adjacent a test position into which a tube is adapted to be moved, means mounting said rotor for rotation about an axis substantially coaxial with a tube in said test position, hammer drive means carried by said rotor and rotatable by said rotor through a path extending circumferentially about a tube in said test position, hammer means connected to said hammer drive means and movable into impacting engagement with a tube in said test position responsive to actuation of said hammer drive means, means for rotating the rotor through an angle sufiicient for the locus of impact of said hammer means on a tube in said test position to extend at least 360 circumferentially around the tube axis, and a controller for actuating said hammer drive .means during rotation of said rotor.

2. Electron tube testing apparatus comprising a rotor 4 adapted to be disposed adjacent a test position into which a tube is adapted to be moved, means mounting said rotor for rotation about an axis substantially coaxial with a tube in said test position, hammer drive means carried by said rotor, a hammer connected to said hammer drive means and movable into engagement with a tube in said test position responsive to actuation of said hammer drive means, means for adjusting the position of said hammer along the axis of a tube in said test position, means for rotating the rotor, and a controller for actuating said hammer drive means operable by rotation of said rotor.

33. Electron tube impact and vibration testing apparatus comprising a shaft adapted to be disposed adjacent a test position into which a tube may be moved, means mounting said shaft for rotation about an axis substantially coaxial with a tube in said test position, a plurality of solenoids carried by said shaft and disposed about the axis of a tube in said test position, each solenoid including a movable armature having a hammer, said hammer engageable with spaced points on a tube in said test position responsive to solenoid control signals, means for rotating said shaft, switching means, and a cam rotatable with said shaft and cooperable with said switching means for generating solenoid control signals.

4. Electron tube impact and vibration testing apparatus comprising a hollow shaft adapted to be disposed with one end adjacent a test position into which a tube may be moved, means mounting said shaft for rotation about an axis substantially coaxial with a tube in said test position, a plurality of solenoids carried by said shaft and disposed about the axis of va tube in said test position, each solenoid including a movable armature having a hammer, said hammers being movable into engagement with spaced points on a tube in said test position responsive to solenoid control signals, means for rotating said shaft, switching means, a cam rotatable with said shaft and cooperable with said switching means for generating solenoid control signals, and tube supporting means including a plunger reciprocable within said hollow shaft to and from engagement with a tube in said test position.

5. Electron tube impact and vibration testing apparatus comprising a shaft adapted to be disposed with one end adjacent to a test position into which a tube may be moved, means mounting said shaft for rotation about an axis substantially coaxial with a tube in said test position, a plurality of solenoids carried by said shaft and disposed about the axis of a tube in said test position, each solenoid including a movable armature having a hammer, said hammers being engageable with spaced points on a tube in said test position responsive to solenoid control signals, a reversible and stallable drive motor for rotating said shaft, a rotation limit member rotatable with said shaft, stationary limit stops associated with said limit member and engageable thereby to limit rotation of said shaft to predetermined fractions of a revolution in opposite directions away from an initial positiorn'stationary solenoid control signal generating switches, and a cam rotatable with the rotor for operating said switches.

6. Electron tube testing apparatus comprising a rotor adapted to be disposed adjacent a test position into which a tube is adapted to be moved, means mounting said rotor for rotation about an axis substantially coaxial with a tube in said test position, hammer drive means carried by said rotor and rotatable by said rotor through a path extending circumferentially about a tube in said test position, a hammer connected to said hammer drive means and movable into engagement with a tube in said test position responsive to actuation of said hammer drive means, means for rotating the rotor, and a controller operable by rotation of said rotor for actuating said hammer drive means.

7. Electron tube testing apparatus comprising a support adapted to be disposed adjacent a tube test position and rotatable relative to a tube in said test position about an axis substantially coaxial with a tube in said test position, hammer drive means carried by said support, hammer means connected to said hammer drive means for movement into impacting engagement with a tube in said test position responsive to actuation of said hammer drive means, means for rotating said support relative to a tube in said test position through an angle sufiicient for the locus of impact of said hammer means on a tube in said test position to extend at least 360 References Cited in the file of this patent UNITED STATES PATENTS 2,281,324 Preston Apr. 28, 1942 10 2,418,437 Vogt Apr. 1, 1947 2,721,971 Francois Oct. 25, 1955 

